Conventionally, chromatograph-mass spectrometers such as liquid chromatograph-mass spectrometers (LC/MS) and gas chromatograph-mass spectrometers (GC/MS) have been preferably used to analyze a sample which contains multiple components. Some mass spectrometers can operate an MSn analysis in which ions are captured and dissociated successively once or multiple times (refer to Non-Patent Document 1 for example) to obtain structural information of sample components separated by chromatography.
When performing an analysis of a mixed sample's component which is similar to a known component, it is first necessary to obtain MSn analysis data of the mixed sample, and then based on that data, select a molecular (component) which has a similar structure to that of a target molecule from many components contained in the sample. This kind of analysis includes, for example, quantitative determination and/or structural analysis of metabolites in the pharmacokinetics studies, and identification of analogous impurities of by-products and/or decomposition products in the synthesis of pharmaceutical compounds.
In the conventional analysis, every MSn spectrum (e.g. MS2 spectrum) obtained for each peak in the chromatogram of a sample is shown one by one on a monitor. An operator looks at the monitor and judges the similarity between the spectrum and the MSn spectrum of the known substance to be targeted by visual comparison. Then the operator selects a candidate for the similar component.
[Non-Patent Document 1] “Liquid Chromatograph-Mass Spectrometer— LCMS-IT-TOF”, [online], Shimadzu Corporation, [Search Date: Apr. 6, 2006], Internet <http://www.an.shimadzu.co.jp/products/lcms/it-tof.htm>
Unfortunately, only a skilled operator with much knowledge and experience can do a manual analysis as described earlier. In addition, since visibly checking every single MSn spectrum obtained from each component requires a huge amount of time and effort, it is difficult to enhance the efficiency of the analysis.
To solve the above-described problem, the present invention intends to provide a method of analyzing mass analysis data for quickly and accurately searching a component similar to a target component based on a result of an MSn analysis for each unknown component in a sample.